Discrepancy between ChronoBody_Forces and ChronoExchange_mkbound_xx

a_meduri2312a_meduri2312
in DualSPHysics v5.0

Hi,

I recently asked a question about evaluating forces from Chrono (https://forums.dual.sphysics.org/discussion/comment/4931#Comment_4931) Using @Alex answer, I was able to evaluate the forces in ChronoBody_Forces and ChronoExchange.

However, for every simulation I have run this far, the angular acceleration I get from floating info is exactly the same as the angular acceleration from ChronoExchange_mkbound. This should be expected as this is the input data that is input into Chrono is the acceleration from Fluid + Mooring Forces

The surprising thing I have noticed is that the output forces ChronoBody_Forces has the moment about y axis. If I plot the the angular acceleration as Moment/(Mass Moment of Inertia), I get that is the exact same as the previous two.

I have attached a plot comparing the acceleration values. (The difference in the points in the blue and red/black is due to timesteps of PartOut vs savevalues in Chrono)

image.png

So, from the previous post, ChronoExchange_mkbound is the input accelerations and ChronoBody_Forces is the output forces/moments. If true, why are they the exact same then?

I have used the angular acceleration as an example. But this issue is observed for all degrees of freedom. From the vtk files, I can clearly see the Chrono Collision and Link_LinearSpring act on the body, so I do not understand why it is not reflected in the force evalutions?


@Asalih3d

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